Collaborative Research: EAGER: Biophysical Constraints on Organism Persistence: Deciphering Heterogeneity of the Local Environment

In this project the PIs will use synchrotron radiation to study respiratory pathogens' persistence in microdroplets during flight between hosts. One of the bacteria that will be studied is Bacillus Calmette-Guérin (BCG, the tuberculosis vaccine). Bacterial persistence has been correlated with factors such as ambient relative humidity, droplet size, fluid composition, bacterial number density, and ambient temperature. A plethora of theorized mechanisms for these persistence correlations are proposed in the literature, ranging from atmospheric exposure, acidity, to access to nutrients, and others. Evaluating these proposed mechanisms is complicated by highly conflicting correlations and results in the literature. To decipher the tremendously effective and robust host-to-host transmission cycles of pathogens through the air, it is key to understand pathogen-laden microdroplets which are made of complex biofluids with interacting compounds. In addition to providing interdisciplinary training for mentees on this project, and educating a new cadre of uniquely trained professionals for the U.S. workforce, the understanding of the fluid micro-environmental conditions that promote or reduce survival of microorganisms opens the door for the rational design of novel detection/sensing and surveillance technologies and fundamentally informs us about the spread and robustness of life that beside its inherent interest can also be used for bioengineering solutions. Here, we seek to actually see through the pathogen-laden microdroplets with synchrotron X-ray platforms developed to enable unprecedented precision for in-situ analysis. The goal is to link mechanistically how microorganisms shape microdroplet residues; where microorganisms are located within such complex heterogeneous environments. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.